Digital video systems generally communicate a sequence of digital images from a source, such as a camera, to a destination, such as a display. The communication can be directly from a camera to a live display or the communication can be time delayed by storing the video and displaying it at a later time. The digital images may be compressed or communicated in their native format.
Various system failures within a digital video system may cause the sequence of images to stop, or to lock-up, resulting in a frame freeze condition. For example, a communications fault between the camera capturing a live video stream and the display showing the live video stream may cause such freeze condition. In some critical applications, it is important for an operator to know quickly that the video system has failed. This may be especially true where a static image on the operator's display may cause the operator to erroneously conclude that scene at the source is simply not changing, when in fact the video system is not operating properly. Some examples of critical applications are security monitoring, medical monitoring, military surveillance, navigation, or manufacturing system tracking.
U.S. Pat. No. 8,165,226 (The Boeing Company) allegedly solves this problem by placing a code into each frame of the video stream. The code counts sequentially from one frame to the next and is embedded into a pixel of each frame. Verification at the destination, or display, of the changing code within the frames of the video stream can confirm that the video stream is not in a frame freeze fault condition prior to display. If a fault condition is detected by the code verification process, an operator can be made aware of the fault. However, such a system is complex and requires that the display is connected to a processor running the code verification process.